alr

topologicalSort.java

@@ -0,0 +1,53 @@
+import java.util.*;
+
+public class topologicalSort{
+    static int N;
+    static int[][] graph;
+    static boolean[] visited;
+    static Stack<Integer> stack = new Stack<>();
+
+    static void dfs(int v){
+        visited[v] = true;
+        for(int i =0;i<N;i++){
+            if(!visited[i] && graph[v][i]==1){
+                dfs(i);
+            }
+        }
+        stack.push(v);
+    }
+
+    static void topoSort(){
+        for(int i=0;i<N;i++){
+            if(!visited[i]){
+                dfs(i);
+        }
+    }
+
+    System.out.println("\nValid execution order");
+    while(!stack.isEmpty()){
+        System.out.print((char)('A'+ stack.pop())+"->");
+    }
+    }
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        System.out.print("\nEnter number of tasks: ");
+        N = sc.nextInt();
+        graph = new int[N][N];
+        visited = new boolean[N];
+
+        System.out.print("ENter number of dependencies: ");
+        int edges = sc.nextInt();
+
+        System.out.println("Enter dependencies (u v means u -> v):");
+        for(int i = 0;i<edges;i++){
+            char u = sc.next().charAt(0);
+            char v = sc.next().charAt(0);
+
+            graph[u-'A'][v-'A'] = 1;
+        }
+        topoSort();
+        sc.close();
+    
+    }
+    
+}